Impact on antioxidant activity of including grape peel flour in a novel sorghum-based extruded food

Abstract The aim of this study was to evaluate the effect of combining grape (Vitis vinifera L.) peel flour (GPF) and the colored sorghum BR305 (brown) flour (CSF) by extrusion and the consequent impact on antioxidants in the final product. The physical properties and bioactive compounds of both raw GPF and blended GPF/CSF extruded materials were investigated. The results before extrusion of raw materials, the antioxidants by ORAC the CSF was 89.111 ± 0.25; GPF before drying 321.033 ± 0.21; GPF flour after drying was 311.022 ± 0.30 µmol Trolox.g−1, respectively. Considering the different treatments (10, 15 and 20% of GPF), the highest values of the compounds obtained: Antioxidant activity, ORAC, was 37.889 ± 0.32 (µmol Trolox.g−1); with 15% of GPF, at 120 °C and 17% moisture processing. ABTS, 12.222 ± 0.14 (µmol Trolox.g−1); with 20% GPF at 140 °C and 19% moisture processing as best processing conditions. Anthocyanins 138.31 ± 0.11 (mg cyanidin-3-glucoside 100 g−1); Total phenolic 307.95 ± 0.11 (mg catechin.100 g−1). The water absorption index was 38.99 ± 0.19, g of gel.(g dry matter)−1 perhaps are sufficient for the preparation of beverages for breakfast or in porridge in order to contribute to the health of the consumer.